1. Field of the Invention
The present invention relates to an optical disc driving apparatus, and more particularly to an optical disc driving apparatus for driving an optical disc to have information memorized in the optical disc, or to retrieve information form the optical disc.
2. Description of the Related Art
Up until now, there have been proposed a wide variety of conventional optical disc driving apparatus of this type one typical example of which is disclosed in Japanese Patent Laying-Open Publication No. H10-149639.
The conventional optical disc driving apparatus comprises a turntable having a central axis and an optical pickup unit movable toward and away from the central axis of the turntable. The turntable is adapted to retain an optical disc under the condition that the central axis of the turntable is axially aligned with the central axis of the optical disc, while the optical pickup unit is adapted to write or retrieve information from the optical disc retained by the turntable.
The conventional optical disc driving apparatus further comprises a stepping motor having a plurality of coils, and a driver IC for controlling the stepping motor to have the stepping motor assume two different operation states consisting of a first operation state to allow the stepping motor to ensure that the optical pickup unit is moved toward and away from the central axis of the turntable, and a second operation state to allow the stepping motor to produce a torque larger than a detent torque to ensure that the optical pickup unit fails to be moved toward and away from the central axis of the turntable.
The optical disc driving apparatus thus constricted as previously mentioned, however, encounters such a problem that the relatively high calorific value tends to be produced by the control currents to be supplied to the coils of the stepping motor in the coils of the stepping motor when the rotation shaft of the stepping motor fails to be moved around its central axis without being affected by the exterior vibration.